s128 of the Constitution requires that any proposed amendment to the Constitution must first be passed by an absolute majority of both House of Parliament, or at least one House if the other House refuses. s128 also imposes a double majority system for change by the people: firstly a majority of electors in a majority of States must approve of the change and, secondly, a majority of all electors nation-wide must also approve of the change. Up to and including 6 November 1999, only 8 out of 44 proposals placed before the Australian people to change the Constitution have received the necessary approval under s128 of the Constitution.

From the outset of federation in 1901, any change to the Constitution was subject to these requirements thus preventing the Commonwealth Government itself from making changes to the Constitution without reference to the people. In other words, the Constitution was protected from any undue and unwanted change by the Australian Parliament without approval by the people at a referendum.

In theory, the United Kingdom Parliament, to, could amend the Constitution which was contained in an Act of that Parliament, the Commonwealth of Australia Constitution Act.[17] The Constitution Act itself, of which the constitution was section 9, could be altered only by the parliament of the United Kingdom, which could also, as a matter of law, alter the constitution itself if it chose to do so.[18] This was also recognised by Quick and Garran in their discussion on restrictions of the amending power in respect of depriving equal representation of the States in the Senate and the minimum number of representatives in the "National Chamber". Quick and Garran indicated that "If unanimity cannot be secured, there yet remains the possibility of resort to the Imperial Parliament for an amendment of the Constitution, dispensing with the necessity for obtaining the consent of all the States".[19] Quick and Garran also assert that "the Commonwealth (of Australia) is only quasi -sovereign, and the amending power, though above the State Governments and above the Federal Government, is below the Imperial Parliament" and that "The amending Power can amend the Constitution, but the Constitution Act is above its reach".[20]

However, since the introduction of the Australia Act 1986 (Cth) that is no longer the case as Section 1 of that Act states:

'No Act of the Parliament of the United Kingdom passed after the commencement of this Act shall extend, or be deemed to extend, to the Commonwealth, to a State or to a Territory as part of the law of the Commonwealth, of the State or of the Territory.'However, the aforementioned section could possibly be repealed. Cheryl Saunders, in a recent article writes, amongst other things, on Australia's independence: 'It was formalised in the passage of the Australia Acts 1986, which made it clear that the British parliament could, or at least would, no longer legislate for Australia.[21] Also, P. H. Lane has indicated:

'.. If we wanted to scrap the existing document[22] altogether, for instance, to become a republic or to end the Federation by abolishing the States, first the Federal Parliament, at the request or with the concurrence of all State Parliaments, should qualify so much of the Australia Acts 1986 (Cth & UK) as stand in the way. Then these Parliaments should request and consent to the United Kingdom Parliament repealing the whole Constitution Act.'[23]The view that the United Kingdom could have amended the Constitution prior to 1986 is also supported by Professor George Winterton. However, Professor Winterton has also indicated that the United Kingdom may not be legally limited to Section 1 of the Australia Act 1986 (UK).[24]

The High Court of Australia also plays a part in the constitutional process. It fills in the details for the day-to-day running of the country, and it adapts the Constitution to the present day.[25] The High Court, for example, has decided that the Commonwealth's power in s. 51(v) over 'postal, telegraphic, telephonic, and other like services', given in 1901, now allows the Commonwealth to control broadcasting (in 1935) and television (in 1965). Thus the High Court has updated the postal power.[26]

However, the Constitution should not be read in isolation. Apart from various Acts of the Commonwealth Parliament, State Constitutions and High Court dicta that add further to the constitutional picture, there are two other very important Acts that impinge on our constitutional arrangements. The Statute of Westminster 1931 (UK) and the Australia Act 1986 (UK) (the latter is mirrored in the Australia Act 1986 (Cth)) are two English Acts that affect Australian constitutional law.[27]